t: use test_must_fail instead of hand-rolled blocks

These test scripts likely predate test_must_fail, and can be
made simpler by using it (in addition to making them pass
--chain-lint).

The case in t6036 loses some verbosity in the failure case,
but it is so tied to a specific failure mode that it is not
worth keeping around (and the outcome of the test is not
affected at all).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t4124-apply-ws-rule.sh

@@ -99,9 +99,8 @@ test_expect_success 'whitespace=warn, default rule' '
 
 test_expect_success 'whitespace=error-all, default rule' '
 
-	apply_patch --whitespace=error-all && return 1
-	test -s target && return 1
-	: happy
+	test_must_fail apply_patch --whitespace=error-all &&
+	! test -s target
 
 '
 

t/t6036-recursive-corner-cases.sh

@@ -195,12 +195,7 @@ test_expect_success 'git detects differently handled merges conflict' '
 	git reset --hard &&
 	git checkout D^0 &&
 
-	git merge -s recursive E^0 && {
-		echo "BAD: should have conflicted"
-		test "Incorrectly merged content" = "$(cat new_a)" &&
-			echo "BAD: Silently accepted wrong content"
-		return 1
-	}
+	test_must_fail git merge -s recursive E^0 &&
 
 	test 3 = $(git ls-files -s | wc -l) &&
 	test 3 = $(git ls-files -u | wc -l) &&

t/t9300-fast-import.sh

@@ -2853,8 +2853,8 @@ test_expect_success 'S: notemodify with garbage after mark commit-ish must fail'
 # from
 #
 test_expect_success 'S: from with garbage after mark must fail' '
-	# no &&
-	git fast-import --import-marks=marks --export-marks=marks <<-EOF 2>err
+	test_must_fail \
+	git fast-import --import-marks=marks --export-marks=marks <<-EOF 2>err &&
 	commit refs/heads/S2
 	mark :303
 	committer $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE
@@ -2865,9 +2865,6 @@ test_expect_success 'S: from with garbage after mark must fail' '
 	M 100644 :403 hello.c
 	EOF
 
-	ret=$? &&
-	echo returned $ret &&
-	test $ret -ne 0 && # failed, but it created the commit
 
 	# go create the commit, need it for merge test
 	git fast-import --import-marks=marks --export-marks=marks <<-EOF &&